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DPChallenge Forums >> Tips, Tricks, and Q&A >> Macro focus af mode types?
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Showing posts 1 - 5 of 5, (reverse)
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 01/11/2006 09:01:49 PM · #1
Ive been doing a lot of macros lately, but often the outside is blurred even when I take it on f9. Mostly just the middle is in focus. Its usually worse the more magnified as you would expect. Its especially apparent on +10. I remember though Af mod has area, center and multi, will using these make a difference and the photometry, average, spot and multi, any of these need changing?

Im currently on:

center af mode
photometry - multi

I can experiment with it I guess, but I was just wondering if anyone had any views/info
 01/14/2006 08:23:22 AM · #2
so no one knows anything?
 01/14/2006 08:30:41 AM · #3
Macros, even at +4, have a very shallow depth of field. Objects a few mm away from the point of focus will be out of focus. The more you magnify, the shallower depth of field you get. Depending on the lens and the object, you could try different agles such that all of the object within the frame was more or less on the same plane of focus. I personally don't have any problems with shallow depth of field in macros. It looks real. I always use manual focus.

Tae care.
 01/14/2006 08:47:35 AM · #4
ok thx
 01/14/2006 12:07:28 PM · #5
As ignite commented, if your "object" is relatively flat (like a coin, for example, or the face of a watch, you should take care to have the object oriented parallel to the sensor plane, so DOF is not an issue. The more obliquely you orient it, the more of an issue you have.

If your setup requires DOF, it's good to remember that DOF extends 1/3 in front and 2/3 behind the point of focus; if you have 3mm of usable DOF and you focus at a point 24mm from the camera, your DOF extends from 23mm to 26mm. This is why we almost always use manual focus for critical macro work; our focus point will not always be on what we consider to be the most important part of the object, but rather on an arbitrary point such that the "important point" falls within the range of the DOF while the actual field of focus is oriented as we visualize it. This is very difficult to do with autofocus.

I will frequently, when doing macros of a static setup, insert a "marker" into the image at the point where I wish to focus, do my focusing, and then remove the marker and shoot. I'll bracket my apertures (working in Av mode if not full manual) to find the one that works best for the shot. The differences can be extreme.

Robt.
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